Abstract: Based on the historical flood documents and records from Han dynasty to Qing dynasty, this paper studies the characteristics of frequency and spatial distribution of the historical flood in Jiangsu province, and then it discusses the influence factors which affect the frequency and distribution. The conclusions can be drawn as follows. Firstly, the flood in historical period almost happened in summer and autumn, so this paper thinks that the abnormal precipitation for a long time, tide disaster caused by tropical cyclone and El Nino events are the main reasons for flood in Jiangsu province. Secondly, the flood frequency in Ming dynasty and Qing dynasty was higher than any other times. Human activities is one of main reasons which caused the flood. Thirdly, the flood frequency in Lixiahe plain, Taihu plain and the region along the Yangtze River were higher than other areas. Because these three areas are all flatness plain that is lower than its surroundings. With the Yangzi Delta developing, the tide effect became weakened, so the flood in the region along the Yangtze River in Ming and Qing dynasty decreased. Before Yuan dynasty the Taihu plain was the area where the flood was serious but after Ming dynasty the most serious area had moved to Lixiahe plain. The reason for the change is the population in Taihu plain was exploded in Song dynasty, people changed the water area into farmland which caused the water area decreased and the flood cannot flow into the sea quickly, so the flood happened frequently. After Ming dynasty the rivers were dredged for several times, so the flood can flow efficiently. The Yellow river which carries numerous sands changed its route in 1128AD; it caused almost the sands settled down in Subei plain especial Lixiahe plain. This area became the flood corridor.